1. Technical Field
The present invention relates to a liquid ejecting head that ejects liquid through nozzle openings, a liquid ejecting apparatus that has a liquid ejecting head, a piezoelectric element for liquid ejecting heads or similar devices, and a method for manufacturing a piezoelectric element.
2. Related Art
A known liquid ejecting head ejects droplets of liquid through nozzle openings by deforming piezoelectric elements to change the pressure in the liquid in pressure chambers that communicate with the nozzle openings. A representative example of a liquid ejecting head is an ink jet recording head, which ejects droplets of ink.
A typical ink jet recording head has a flow channel substrate, and also has pressure chambers and piezoelectric elements on either side of the flow channel substrate. The pressure chambers communicate with nozzle openings. The piezoelectric elements operate to deform diaphragms and change the pressure in the ink filled in the pressure chambers. As a result, droplets of the ink are ejected through the nozzle openings.
In a typical structure, each piezoelectric element has a first electrode, a piezoelectric layer, and a second electrode all disposed on a diaphragm, and the first electrode and the second electrode are coupled to a wiring layer for coupling with wiring that leads to a driving IC and other components (e.g., see JP-A-2008-114370, JP-A-2009-172878, and JP-A-2009-196329).
When the wiring layer has an adhesion layer made of nickel-chromium or a similar material, patterning the adhesion layer by wet etching causes electrochemical corrosion to occur at the boundaries between the adhesion layer and the electrodes because the wet etching process uses an acid as etchant. This sort of damage may lead to events such as detachment of the electrodes or the wiring layer.
The use of an acid to wet-etch the adhesion layer may also affect the piezoelectric properties because the acid can damage the piezoelectric element.
Furthermore, it is costly to form the wiring layer by gas-phase processes such as sputtering.
Such problems are not unique to ink jet recording heads. Similar problems may also be encountered with liquid ejecting heads used with liquids other than ink. Like piezoelectric elements for liquid ejecting heads, piezoelectric elements for other devices also have similar problems.